Background: Reports suggest a high prevalence of substance misuse in psychotic disorders but few studies examine comorbidity at onset of psychosis.
Aims: To identify the prevalence and pattern of substance use and misuse in first-episode psychosis, and relationships with diagnosis, mode of presentation and demographic variables.
Method: Consensus diagnoses for 168 subjects presenting with first-episode psychosis were made using ICD-10 diagnostic criteria. Information on substance use and misuse was obtained from multiple sources. We examined associations between substance misuse, diagnosis and demographic factors.
Results: Criteria for drug use, drug misuse or alcohol misuse were met by 37% of the sample. One-year prevalence rates were 19.5% (drug misuse) and 11.7% (alcohol misuse). Thirteen subjects (8.4%) received a primary diagnosis of substance-related psychotic disorder; a significant increase compared with an earlier cohort from the same catchment area. Drug misuse was associated with younger age of onset of psychosis, male gender and non-African-Caribbean ethnicity.
Conclusions: This study confirms high rates of substance misuse at onset of psychosis. There is evidence for an increase in diagnosis of substance-related psychotic disorders over time. Those most at risk of substance misuse are young males.